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(11) | EP 0 940 904 A3 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | Emergency lighting system |
| (57) An emergency lighting system capable of performing self-testing is disclosed. The
system comprises a main power supply and a plurality of lighting units each having
mains failure circuitry to monitor the main supply and to connect the lighting unit
for operation to an auxiliary power supply in the event of failure of the main power
supply. Each lighting unit further includes a testing circuit operative, on receipt
of a command, to assess the condition of operational readiness of the lighting unit.
The system has a control unit. A signal line connects the control to the testing circuit
of one or more of the lighting units. In operation, the control unit applies signals
to the signal line and detects signals which have been applied to the signal line
by a testing circuit. Each one of the testing circuits is identified as from the others
by an address. On detection of a signal indicating its address on the signal line,
each testing circuit applies to the signal line a signal indicative of the operational
readiness of the associated lighting unit. |